Post from the Amiga dev:
"Phil Mercurio
January 11, 2016
Some notes on the Amiga version: I was the only Amiga programmer at FTL. I worked from home because FTL didn’t own an Amiga, and I wasn’t about to drag my computer to and from the office each day. I’m currently working from home again, using the same desk (different computer, though :-).

There were two enhancements the Amiga had over the ST that I wanted to take advantage of. The first was the graphics accelerator (the blitter). I started at FTL in February of 1987 and spent months on replacing the C and assembly graphics code with code that used the blitter. One day, not too long before the ST version was released, a bunch of the blitter code started working and suddenly I could play through most of the game! That blew my mind. I loaded my Amiga into the car and drove to the office to show Wayne and the rest of the gang. I think they were a little jealous because the game graphics already ran smoother on the Amiga than they did on the ST.

The second enhancement was the stereo sound hardware. I immediately dismissed the idea of modeling sound attenuation through the walls as being too hard. As a result monsters walking around on the other side of a wall sound like they’re in the same room, which is scary. Since DM movement is on a grid, I only needed to compute the attenuation for a finite set of positions relative to the player. I chose a square radius of 12, so I needed a 25×25 table of volumes relative to the right ear. To get the volume for the left ear, just index into the table with (-x, y) (the positive Y axis is in front of the player).

For higher-frequency sounds, phase differences between the ears are important for localization. However, for lower frequency sounds, only the difference in volume is relevant. The sounds used in DM didn’t even extend into the higher frequencies, so volume difference was all I needed. Rather than come up with a fancy formula, I found a line plot of volume vs. azimuth in a psychophysics textbook, blew it up with a photocopier, and used a ruler to read the volume for each angle directly off the line plot. Applying an attenuation for the distance from the player gave me the final values for the 25×25 table. According to comments in the code, the stereo sound code took just a couple of days around July 22nd, 1988. From the feedback I’ve gotten regarding how much people loved the experience of chasing monsters around by sound, it was well worth the effort!"

Last edited by kamelito; 13 January 2016 at 18:51.
Reason: Add post of Amiga dev